TOPIC: Crackling Speaker Following LED

Hello,

I'm having a strange issue. I recently finished building my first saber. it's a Royal Blue/Red/White Tri-Cree (with the intention of primarily running purple). I'm using the NBv4 soundboard, and the second and third banks were red and blue, respectively. it worked for a few days, but then two or three days ago I noticed that the second bank was making crackling sounds in the speaker. over time it got worse, so now it sounds rather like radio static with a feedback loop (progressively gets louder over seconds). I tested my speaker, and it's working fine.

So then I tried switching the light settings between bank 2 and bank 3. the crackling sounds followed the red LED. I assume there must be a wiring issue but there's also a chance it's in one of my components. has anyone else experienced something like this?

It's very important to me to figure this out as I want to take it with me to school in september, and I won't be able to have soldering equipment up there.

Thank You!

process of elimination, the simplest answer is most often true.

1.) is it possible that the speaker is shifting inside the hilt or is the crackle very consistent? I've had speakers behave similarly and it turns out it was simply vibrating against the hilt in one place or another (usually the pommel.)

2.) if the crackle is very consistently associated with the red die, does that particular die have any exposed connections? or are there any exposed connections near the space the speaker rests?

3.) is it possible there is a bridge or arc between the speaker connections on the board, are the connections solid?

your speaker will translate any errant electrical signal as static. I'd first make sure that the speaker connections at the board and speaker are insulated and move up the line from there.

I'm spitballing without having the saber in my hand.

I've already ruled out the first and third possibilities. I've been considering opening up the LED module, but hasn't yet. So I guess I'll try that next, thanks. Would it help if I made a video? (Assuming the LED module doesn't seem to have a problem).

how are you insulating your speaker connections? if its picking up electrical feed back from that die it might be conducting through the hilt itself, aluminum is a fairly good conductor. Beefing up the insulation on those connections could turn the trick for you.

I've put gaffer's tape between the speaker body and the contacts, and covered the soaker as well as possible, plus covering the contacts in 2 layers of tape. But it still it outside the hilt. I've also checked the board contacts under a magnifier and there seems to be no crossing. I just checked the LED module and while some of connections are a little hairy, nothing appears to be close enough together to cause any issue. All of the wires are securely attached, as well.

Might be something as simple as not using a big enough resistor on Red or using a battery that can't handle the load. You'll need to provide more specifics on your components.

I find it a little interesting that you only hear the crackling on the red, but not when running the purple? The red would be on when running the purple bank. I'm also assuming that you have a power extender since it sounds like you're running the 3 LEDs independently? I agree with Kouri that more specifics and/or photos are needed.

Kouri beat me to it, those were gonna be my next suggestions. Resistor and battery.

I'm leaving in a hurry today but I'll try to get some pictures up this evening sometime. My purple does crackle, but not as much as the red. My blue crackles only when I trigger FoC which has a very very light red tinge to it, but the crackling sticks around after that for a little bit.

I'll also get a part list made when I'm back, just thought I'd keep you updated.

Ok, here's some photos. I sized them down to SF requirements and they seem very small, so let me know if I can do something to make this easier.

This is my full saber outside it's casing except the switch section




Here's the LED Wiring. Blue wire goes to White LED, Yellow wire goes to the Red LED, and green goes to the Blue LED. White was meant to be FoC, so it's hooked up to the PEx down the line.




Here's the power extender:




I can't get into the switch body without some more serious disassembly, but they are wired with heatshrink and according to SF and NBv4 specification. Next up is the Sound Card. wires don't look too secure on the top side but underneath are very well soldered, with hairs cut off.




and here's a shot without the tape to see the main PEx line




Lastly, the speaker. normally I have gaffer's tape over the connections here

So did you put a resistor on the red LED? I'm not seeing one.

I did put resistors. they're wrapped in heatshrink and gaffer's tape, and they hang through the switchsection with the rest of the wire bundle:






I bought 7 total of these as they were the best specs I could find at a reasonable size, I believe it's 1.3 ohms at 5%? :




I have one on the wire that goes to the red, two going to the blue, and three going to the white. all wired in parallel as needed for each led.

The red one would need to be at least 2W, and the image you posted looks suspiciously like a 1/4W.

Well, that is extremely plausible. I haven't done almost any electronics before this and I had a really hard time finding resistors that were close to the requirements. I'll see if I can get a hold of some with the proper specs. do you happen to have recommendations for where to get the right kinda thing?

Thank You!!

If you picked up the NB from the usual shop, they also carry common saber resistors. Otherwise, mouser.com offers metal oxide resistors in just about any value you can ask for.

You'll want the wattage to be greater than the numerical value you calculated for resistance - roughly twice as much. You can round down slightly, or go infinitely higher, but higher wattage resistors take up more space.

What Kouri Said.

Assuming your typical Cree Red die, a 1ohm 2watt works perfectly.

I'd also recommend a .5ohm on the white, 2-3 watts